|
(11) | EP 0 181 446 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
|
|
| (54) |
Radiation image recording and read-out system Strahlungsbildaufnahme- und Wiedergabesystem Système pour l'enregistrement et la reproduction d'image de rayonnement |
|
|
|||||||||||||||||||||||||||||||||||
| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
[0001] This invention relates to a radiation image recording and read-out system for exposing a stimulable phosphor to a radiation to have a radiation image stored therein, scanning the stimulable phosphor with a stimulating ray to cause the stimulable phosphor carrying the radiation image to emit light in the pattern of the radiation image stored therein, reading out the emitted light to obtain an electric signal, and reproducing a visible image by use of the obtained electric signal.
[0002] When certain kinds of phosphors are exposed to a radiation such as X-rays, oc-rays, (3-rays, y-rays or ultraviolet rays, they store a part of the energy of the radiation. Then, when the phosphor which has been exposed to the radiation is exposed to a stimulating ray such as visible light, light is emitted from the phosphor in proportion to the stored energy of the radiation. A phosphor exhibiting such properties is referred to as a stimulable phosphor.
[0003] As disclosed in U.S. Patent Nos. 4,258,264, 4,276,473 and 4,315,318 and Japanese Unexamined Patent Publication Nos. 56(1981)-104645 and 56(1981)-11395, it has been proposed to use the stimulable phosphor for recording a radiation image of the human body for medical diagnosis. Specifically, the stimulable phosphor is first exposed to a radiation to have a radiation image stored therein, and is then scanned with a stimulating ray which causes it to emit light in the pattern of the stored image. The light emitted from the stimulable phosphor upon stimulation thereof is photoelectrically detected and converted to an electric image signal, which is processed as desired to reproduce a visible image of a quality suitable for viewing and diagnostic purposes. The final visible image may be reproduced in the form of a hard copy or may be displayed on a cathode ray tube (CRT). The stimulable phosphor sheet used in this method may be in any of various forms such as a panel, drum or the like, which are herein generally referred to as sheets. In this radiation image recording and reproducing method, the stimulable phosphor sheet is used to temporarily store the radiation image in order to reproduce the final visible image therefrom on a final recording medium. For economic reasons, therefore, it is desirable that the stimulable phosphor sheet be used repeatedly.
[0004] In order to reuse the stimulable phosphor sheet, the radiation energy remaining on the stimulable phosphor sheet after it is scanned with a stimulating ray to read out the radiation image stored thereon should be eliminated or erased by the method described, for example, in Japanese Unexamined Patent Publication No. 56(1981)-11392 or 56(1981)-12599. Practically, it is possible to save manpower by supplying the stimulable phosphor sheet to an image erasing apparatus by use of a conveying means such as a belt conveyor after the radiation image is read out from the stimulable phosphor sheet, and returning the stimulable phosphor sheet to the image recording section by use of a similar conveying means after the radiation image remaining on the stimulable phosphor sheet is erased.
[0005] In general, however, it is not easy to design and manufacture a conveying means which can convey a sheet material like the stimulable phosphor sheet without any failure due to clogging, sheets caught at an intermediate point, or the like. Further, the stimulable phosphor sheet must be conveyed in the intact form without being scratched or flawed. This also makes it difficult to design and manufacture the conveying means. Furthermore, it sometimes happens that some phosphor sheets are processed for reproducing the radiation images therefrom immediately after the radiation images are recorded thereon, and some are processed later together with the others. As a result, the sequence of using the phosphor sheets is disordered, and the new and old phosphor sheets are sent in the mixed form to the image recording section. In this case, it is impossible to obtain reproduced images of a uniform quality since the quality of the reproduced images differs between the new and old phosphor sheets. Further, it is desired to replace the old phosphor sheets with new ones when necessary. For this purpose, it is necessary to inspect the quality of images reproduced from the respective phosphor sheets or to control the number of repetitions of the recording operations for the respective phosphor sheets, thereby to determine whether to replace the phosphor sheets with new ones or to reuse them for further recording operations. However, it is very troublesome to conduct quality control for individual phosphor sheets.
[0006] Further, in a movable X-ray diagnostic station such as a travelling X-ray diagnostic station in the form of a vehicle like a bus which is provided with the radiation image recording and read-out system and travels for recording radiation images for the purpose of collective medical examination, the amount of the recording materials capable of being loaded on the movable radiographic station is limited. Therefore, it would be desirable to load stimulable phosphor sheets which can be used repeatedly on the movable radiographic station, once store the radiation images of the objects on the phosphor sheets, transfer the electric image signals read out from the phosphor sheets into a recording medium having a large storage capacity, such as a magnetic tape, and reuse the phosphor sheets for further recording and read- out operations, thereby to obtain the radiation image signals of many objects. In this case, it would not be necessary to load a number of stimulable phosphor sheets or panels having a relatively large size (for example, having a size of a conventional X-ray film cassette).
[0007] Particularly, when the elements of the system, e.g. the reusable recording materials formed of a stimulable phosphor, the image recording section for exposing each recording material to a radiation passing through the object, the image read- out section for reading out the radiation image stored in the recording material, and the erasing means for erasing the radiation energy remaining on the recording material after the read-out step to again record another radiation image thereon, are combined into one unit, the system can easily be loaded on the movable radiographic station for travelling to conduct medical examinations and can also be easily installed in a hospital or the like. This is very advantageous in practical use.
[0008] Thus the present invention provides a radiation image recording and read-out system comprising:
(a) a supporting material provided on at least one part therepf with a stimulable phosphor layer capable of storing a radiation image;
(b) an image recording section for exposing said stimulable phosphor layer to a radiation passing through an object to store on said stimulable phosphor layer a radiation transmission image of said object;
(c) an image read-out section provided with a stimulating ray source, means for scanning said stimulable phosphor layer carrying said radiation image stored thereon in a first direction with a stimulating ray from said source, and a photo- electric read-out means for obtaining an electrical image signal by reading out light emitted from said stimulable phosphor layer on the scanning and stimulation thereof with said stimulating ray;
(d) an erasing means;
(e) means for moving said supporting material relative to said read-out section from a start position and in a second direction substantially perpendicular to said first direction thereby to allow two-dimensional scanning and stimulation of said stimulable phosphor layer with said stimulating ray; and
(f) means for returning said supporting material and said read-out section to said start position after the radiation image is read out from said stimulable phosphor layer, whereupon said erasing means may operate to eliminate the radiation image remaining on said stimulable phosphor layer prior to further image recordal thereon.
[0009] In the system of the invention means (e) may conveniently operate either to move the supporting material with the read-out section being maintained stationary or to move the read-out section with the supporting material being maintained stationary.
[0010] In the present invention, the electric image signal obtained in the image read-out section may then be once stored on a recording medium such as a magnetic tape or a magnetic disk, displayed on a CRT or the like to immediately observe the radiation image, or permanently recorded as a hard copy on a photographic material or the like by use of a reproducing apparatus. The reproducing apparatus may be directly coupled with the system in accordance with the present invention, installed separately from the system for conducting reproduction via a memory, or placed at a remote position for conducting reproduction through radio communication. In the case mentioned last, it is possible, for example, to reproduce the radiation image recorded in the movable X-ray diagnostic station by use of a radio signal receiver in a hospital, and informing the results of diagnosis conducted by the radiologist to the movable X-ray diagnostic station through radio communication.
[0011] In the radiation image recording and read-out system in accordance with the present invention, the recording materials formed of stimulable phosphor layers for recording radiation images therein are used and reused fixed on a supporting material. Since the recording materials are used and reused in good order unlike the phosphor sheets which are used in the discrete form, it is possible to always obtain reproduced images of a uniform, stable quality without any risk of damage to the recording materials. Further, the system is easy to conduct quality control since, when the stimulable phosphor layers are deteriorated, all layers can be replaced by new ones. Since the recording materials are built in the system, it is easy to handle them and to operate the system. Furthermore, since the system has a simple construction, it is easy to design and manufacture, small in size and light in weight. Accordingly, the system in accordance with the present invention is very suitable for installation in a movable radiographic station, a hospital, or the like. This is very advantageous in practical use.
[0012] The stimulable phosphor referred to in this invention means a phosphor which is able to store radiation energy upon exposure thereof to such radiation as X-rays, --rays, (3-rays, y-rays or ultraviolet rays, and then emits light in proportion to the stored energy of the radiation upon stimulation with a stimulating ray such as a visible ray.
[0013] In the present invention, in order to improve the signal-to-noise ratio of the image signal obtained, it is desirable to make the wavelength distribution of the stimulating ray different from and far apart from the wavelength distribution of the light emitted from the stimulable phosphor. Therefore, it is preferable that the stimulating ray and the stimulable phosphor be selected to satisfy this requirement. Preferably, the stimulable phosphor should emit light having a wavelength within the range between 300nm and 500nm, and the wavelength of the stimulating ray should be within the range between 450nm and 700nm.
[0014] As the stimulable phosphor capable of emitting light aving a wavelength within the range between 300nm and 500nm, or example, rare earth element activated alkaline earth metal fluorohalide phosphor is preferred. One example of this phosphor is, as shown in Japanese Unexamined Patent Publication No. 55(1980)-12143, a phosphor represented by the formula
wherein X is at least one of C1 and Br, x and y are numbers satisfying O<x+y:-50.6 and xY=FO, and a is a number satisfying 10-6≦a≦5x10-2. Another example of this phosphor is, as shown in Japanese Unexamined Patent Publication No. 55(1980)-12145, a phosphor represente by the formula (Ba,+x,M\)FX:yA wherein M" is at least one of Mg, Ca, Sr, Zn and Cd, X is at least one of Cl, Br and I, A is at least one of Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb and Er, x is a number satisfying 0#x%0.6, and y is a number satisfying = 0≦y≦0.2. Further, as the stimulable phosphor can be used ZnS:Cu,Pb; BaQ-xA1203:Eu wherein 0.8≦x≦10; and M"O.xSi02: A = wherein M" is Mg, Ca, Sr, Zn, Cd or Ba, A is Ce, Tb, Eu, Tm, Pb, TI, Bi or Mn, and x is a number satisfying 0.5≦x≦2.5, as shown in Japanese Unexamined Patent Publication No. 55(1980)12142. Furthermore, as the stimulable phosphor can be used LnOX:xA wherein Ln is at least one of La, Y, Gd and Lu, X is at least one of CI and Br, A is at least one of Ce and Tb, x is a number satisfying O<x<0.I, as shown in Japanese Unexamined Patent Publication No. 55(1980)-12144. Among the above enumerated phosphors, the rare earth element activated alkaline earth metal fluorohalide phosphor is the most preferable, among which barium fluorohalides are the most preferable in view of the high intensity of emission of light.
[0015] Further, barium fluorohalide phosphors added with a metal fluoride as disclosed in Japanese Unexamined Patent Publication Nos. 56(1981)-2385 and 56(1981)-2386, or barium fluorohalide phosphors added with at least one of a metal chloride, a metal bromide and a metal iodide as disclosed in Japanese Unexamined Patent Publication No. 56(1981)-74175 are also preferable because of their improved light emitting characteristics.
[0016] It is also desirable to color the stimulable phosphor layer constituting the recording material made of the above phosphor by use of pigments or dyes to improve the sharpness of the image obtained thereby as disclosed in European Patent Publication No. 0021174.
[0017] Certain embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings, in which:
Figure 1 is a schematic view showing a first embodiment of a radiation image recording and read-out system in accordance with the present invention, and
Figure 2 is a schematic view showing the second embodiment of the system in accordance with the present invention.
[0018] In the present invention, it is possible to use one recording material fixed on a plate-like supporting material, and repeat the image recording, read-out, and erasihg steps for the recording material, as shown in Figures 1 and 2.
[0019] In Figure 1 showing the first embodiment of the system in accordance with the present invention, a recording member 703 provided with a stimulable phosphor layer 702 on the surface of a stationary supporting material 701, which is made of a plate-like radiation transmitting material, is used to record radiation images. A radiation source 704 is opposed to the supporting material 701 of the recording member 703. The radiation source 704 may be an X-ray source or the like, and projects a radiation transmission image of an object 705, which is positioned between the radiation source 704 and the recording member 703, onto the phosphor layer 702 through the supporting material 701 to have the radiation image stored on the phosphor layer 702. On the phosphor layer side of the recording member 703 are positioned a stimulating ray source 706 for emitting a stimulating ray such as a laser beam, a light deflector 707 formed of a galvanometer mirror or the like for deflecting the stimulating ray emitted from the stimulating ray source 706 in the width direction of the recording member 703, a photodetector 708 for reading out the light emitted from the phosphor layer 702 upon stimulation thereof by the stimulating ray, and a light transfer means 709 for guiding the light emitted from the phosphor layer 702, which are mounted on a common stage (not shown). The photodetector 708 may be formed of a head-on type photomultiplier, a photoelectric amplification channel plate or the like, and photoelectrically detects the light emitted from the phosphor layer 702 upon stimulation thereof and guided by the light transfer means 709.
[0021] Patent No. 4,346,295, and Japanese Unexamined Patent Publications Nos. 55(1980)-87970 and 56(1981)11395/6/7/8, and may be used by the method disclosed therein. An erasing light source 710 is opposed to the phosphor layer 702 of the recording member 703, and the aforesaid stage also supports a cylindrical cleaning roller 711 which is rotated in the direction of the arrow by a driveunit (not shown). The erasing light source 710 emits light having a wavelength within the stimulation wavelength range of the phosphor layer 702 onto the phosphor layer 702 to cause it to emit the radiation energy stored thereon. The erasing light source 710 may be formed, e.g., of a tungsten-filament lamp, halogen lamp, infrared lamp, or laser source as described in Japanese Unexamined Patent Publication No. 56(1981)11392. Since the radiation energy stored on the phosphor layer 702 can also be eliminated by heating it as disclosed, for example, in Japanese Unexamined Patent Publication No. 56(1981)-12599, the erasing light source 710 may be replaced bya heating means. The cleaning roller 711 rotates and moves in contact with the recording member 703 to remove dust from the surface of the phosphor layer 702. If necessary, the cleaning roller 711 may be of an electrostatic attraction type.
[0022] The system shown in Figure 1 is operated as described below. After the object 705 is positioned between the recording member 703 and the radiation source 704, the radiation source 704 is turned on to cause the phosphor layer 702 to store the radiation transmission image of the object 705. After the recording of the radiation image is over, the stimulating ray source 706 is turned on to scan the phosphor layer 702 with the stimulating ray. Scanning is conducted in the width direction of the recording member 703 (main scanning) by the light deflector 707, and also in the vertical direction of the recording member 703 (subsidiary scanning) by the downward movement of the stage carrying the stimulating ray source 706, the light deflector 707, the photodetector 708, the light transfer means 709 and the cleaning roller 711. The stage can be easily formed by use of a known linear movement mechanism. Upon exposure to the stimulating ray, the phosphor layer 702 emits light in the pattern of the radiation image stored thereon. The emitted light is inputted to the photodetector 708 via the light transfer means 709, and an electric signal corresponding to the radiation image stored on the phosphor layer 702 is obtained from the photodetector 708. When the stage is moved down to conduct the subsidiary scanning, the cleaning roller 711 mounted on the stage is rotated to clean the surface of the phosphor layer 702. When the image read-out is finished and the whole surface of the phosphor layer 702 has been cleaned, the stage is returned to the waiting position above the recording member 703. Thereafter, the erasing light source 710 is turned on for a predetermined length of time, and the phosphor layer 702 is exposed to the erasing light emitted therefrom to eliminate the radiation energy of the radiation image remaining on the phosphor layer 702 after the read-out step, the radiation emitted from radioactive isotopes such as 266Ra and 4°K existing in trace amounts in the stimulable phosphor, and environmental radiations stored in the stimulable phosphor. In this way, the phosphor layer 702 is recovered to the condition usable for recording a further radiation image. The recording member 703 which is now free from any radiation energy and dust is reused to record a radiation image.
[0023] In the embodiment shown in Figure 1, since the stimulable phosphor is not moved, the mechanism is very simple, and the system can be easily designed and manufactured. Further, since one recording material is used repeatedly, the sheet control is easy and uniform visible images can be obtained.
[0024] The electric image signal obtained from the photodetector may immediately be sent to a reproducing apparatus to reproduce the radiation image as a hard copy or display it on a CRT, or may be digitized and temporarily stored on a high-density recording medium such as a magnetic tape, magnetic disk or optical disk to later reproduce the radiation image therefrom. When the system in accordance with the present invention is loaded on a traveling X-ray diagnostic station or the like for obtaining radiation images for medical diagnosis, it is possible to reduce the amount of equipment to be loaded on the traveling station by conducting the readout and storing of the electric image signals on the high-density recording medium at the site of the recording and read-out operation, and bringing the recording medium to a medical center or the like for repro- ' ducing the radiation images. The electric image signals may also be simultaneously inputted to the reproducing apparatus and the recording medium. Namely, when the system is used in a hospital, the electric image signals may be transferred from the recording and read-out station to the recording medium storage station where the image signals are temporarily stored in a recording medium and, at the same time, they may be transferred to the reproducing apparatus, e.g. a CRT, in the diagnostic room in order to use them immediately for diagnosis.
[0025] It is possible and preferable for obtaining a radiation image having a high diagnostic efficiency and accuracy to process the electric image signal in order to intensify the image and change the contrast. In the present invention, it is preferable to conduct the frequency processing as disclosed in U.S. Patent No. 4,315,318 and Japanese Unexamined Patent Publications Nos. 55(1980)-87970, 56(1981)-75137, 56(1981)-75139, 56(1981)-75141, 56(1981)104645 and 56(1981)-11396/7/8 and/or the gradation processing as disclosed in U.S. Patent Nos. 4,302,672, 4,276,473 and 4,310,886.
[0026] In order to obtain a radiation image having an excellent diagnostic efficiency and accuracy, it is preferable to investigate the recording condition or the recording pattern of the radiation image stored on the stimulable phosphor sheets before conducting the read-out, and set the read-out gain of the photoelectric read-out means, the scale factor, and the signal processing conditions based on the recording condition or pattern. For this purpose, it is proposed to read out the pattern of the radiation image in advance by use of a stimulating ray of low energy (this operation is referred to as the preliminary read-out), and then to determine the read-out condition and conduct the read-out for obtaining aradiation image for use in diagnosis (this operation is referred to as the final readout), as disclosed in EP-A-77677. In the present invention, the preliminary read-out may be conducted for example by using the image read-out section both for preliminary read- out and for final readout:
[0027] Figure 2 shows the second embodiment of the system in accordance with the present invention, in which the susbsidiary scanning for reading out the radiation image is conducted by moving the recording material with respect to the stimulating ray source and image read-out apparatus which are fixed in the image read-out zone. Like the system shown in Figure 1, the system shown in Figure 2 employs a recording member 803 comprising a stimulable phosphor layer 802 formed pn a supporting material 801 made of a radiation transmitting material, and is provided with a radiation source 804, a stimulating ray source 806, a light deflector 807, a photodetector 808, a light transfer means 809, an erasing light source 810, and a cleaning roller 811, which are of the same types as those employed in Figure 1. However, unlike the embodiment shown in Figure 1, the stimulating ray source 806, the light deflector 807, the photodetector 808, and the light transfer means 809 are fixed and do not move. The edges of the recording member 803 are fitted to the central grooves 813 of two vertically extending rails 812, and the recording member 803 can be vertically moved along the rails 812 by use of a linear movement mechanism (not shown) such as a rack-pinion mechanism. After the recording member803 is exposed to a radiation coming from the radiation source 804 through an object 805 to have a radiation image stored thereon, the recording member 803 is scanned with the stimulating ray to read out the radiation image. At thistime,the main scanning is conducted by use of the light deflector 807 in the same way as in Figure 1, and the subsidiary scanning is effected by moving up the recording member 803 by use of the linear movement mechanism. As the recording member 803 is moved, the rotating cleaning roller 811 contacts it to remove dust therefrom. After the image readout is finished and the recording member 803 is returned downward, the erasing light source 810 is turned on to erase the residual radiation image on the recording member 803.
[0028] In the embodiment of Figure 2, the stimulable phosphor is moved to conduct the subsidiary scanning by moving the plate-like supporting material. The movement mechanism of this type can be formed more easily than a mechanism for conveying the sheet-like phosphors one by one.
[0029] In the embodiments shown in Figures 1 and 2, the stimulable phosphor is provided on the supporting material made of a radiation transmitting material and positioned on the side of the supporting material opposite to the radiation source. However, this configuration may be changed as desired. For example, the stimulable phosphor may be formed on a supporting material made of a material which cannot transmit a radiation, and may be positioned on the side facing the radiation source. In this case, it is possible to form the system so that, afterthe object moves away from the recording material, the stimulating ray source and the read-out apparatus are moved to the vicinity of the recording material. If the supporting material is pervious to the stimulating ray and the light emitted from the stimulable phosphor upon stimulation thereof, it is possible to position the radiation source on the side facing the stimulable phosphor, and position the read-out apparatus on the side facing the supporting material.
[0030] In the embodiments of Figures 1 and 2, since only one recording material is used repeatedly, it can be easily replaced with a new one when the quality of the visible image reproduced therefrom drops. Thus, these embodiments greatly facilitate the quality control of the recording material.
[0031] In these embodiments, after the movement of the phosphor relative to the image read-out section conducted for the subsidiary scanning is finished for one radiation image, the phosphor and the image read-out section are returned to the original position with respect to each other, and the subsidiary scanning movement is repeated. The movement for returning them to the original position corresponds to the movement of phosphor sheets for passing through the read-out section one after another in the above-mentioned embodiments in which many phosphor sheets are formed on the supporting material.
(a) a supporting material (701) provided on at least one part thereof with a stimulable phosphor layer (702) capable of storing a radiation image;
(b) an image recording section for exposing said stimulable phosphor layer to a radiation passing through an object (705) to store on said stimulable phosphor layer a radiation transmission image of said object.
(c) an image read-out section provided with a stimulating ray source (706), means (707) for scanning said stimulable phosphor layer carrying said radiation image stored thereon in a first direction with a stimulating ray from said source, and a photoelectric read-out means (708, 709) for obtaining an electrical image signal by reading out light emitted from said stimulable phosphor layer on the scanning and stimulation thereof with said stimulating ray;
(d) an erasing means (710);
(e) means for moving said supporting material (701) relative to said read-out section from a start position and in a second direction substantially perpendicular to said first direction thereby to allow two-dimensional scanning and stimulation of said stimulable phosphor layer with said stimulating ray; and
(f) means for returning said supporting material (701) and said read-out section to said start position after the radiation image is read out from said stimulable phosphor layer, whereupon said erasing means (710) may operate to eliminate the radiation image remaining on said stimulable phosphor layer prior to further image recordal thereon.
(a) ein Trägermaterial (710), das zumindest auf einem Teil mit einer anregbaren Leuchtstoffschicht (702) versehen ist, die ein Strahlungsbild zu speichern vermag;
(b) einen Bildaufzeichnungsabschnitt, mit dem die anregbare Leuchtstoffschicht einer durch ein Objekt (705 gelaufenen Strahlung ausgesetzt wird, um in der anregbaren Leuchtstoffschicht ein Strahlungstransmissionsbild des Objekts zu speichern;
(c) einen Bildleseabschnitt, ausgestattet mit einer Anregungsstrahlenquelle (706), einer Einrichtung (707) zum Abtasten der das in ihr gespeicherte Strahlungsbild tragenden anregbaren Leuchtstoffschicht mit einem von der Quelle kommenden Anregungsstrahl in einer ersten Richtung, und einer photoelektrischen Leseeinrichtung (708, 709), mit der ein elektrisches Bildsignal erhalten wird, indem Licht gelesen wird, welches von der anregbaren Leuchtstoffschicht bei Abtastung und ihrer Anregung durch den Anregungsstrahl emittiert wird;
(d) eine Löscheinrichtung (710);
(e) eine Einrichtung zum Bewegen des Trägermaterials (701) relativ zudem Leseabschnitt von einer Startposition aus und in eine zweite Richtung, die im wesentlichen senkrecht zu der ersten Richtung verläuft, um so eine zweidimensionale Abtastung und Anregung der anregbaren Leuchtstoffschicht mit dem Anregungsstrahl zu erreichen; und
(f) eine Einrichtung zum Zurückführen von Trägermaterial (701) und Leseabschnitt in die Startposition, nachdem das Strahlungsbild aus der anregbaren Leuchtstoffschicht ausgelesen wurde, woraufhin die Löscheinrichtung (710) betätigbar ist, um vor einer weiteren Bildaufzeichnung auf der anregbaren Leuchtstoffschicht von dieser das Rest-Strahlungsbild zu entfernen.
(a) un matériau de support (701), sur au moins une partie duquel se trouve disposée une couche de substance stimulable luminescente (702) capable de mémoriser une image de rayonnement;
(b) une section d'enregistrement d'images servant à exposer ladite couche de substance luminescente stimulable à un rayonnement traversant un objet (705) de manière à mémoriser, sur ladite couche de substance luminescente stimulable, une image dudit objet, obtenue par transmission du rayonnement;
(c) une section de lecture d'images, comportant une source (706) d'un rayonnement de stimulation, des moyens (707) servant à balayer, dans une première direction, ladite couche de substance luminescente stimulable, sur laquelle est mémorisée ladite image de rayonnement, par un rayon de stimulation produit par ladite source, et des moyens de reproduction photoélectrique (708, 709) servant à obtenir un signal d'image électrique, au moyen de la lecture d'une lumière émise par ladite couche de substance luminescente stimulable, lors du balayage et de la stimulation de cette couche par ledit rayon de stimulation;
(d) des moyens d'effacement (710);
(e) des moyens pour déplacer ledit matériau de support (701) par rapport à ladite section de lecture depuis une position de départ et dans une seconde direction sensiblement perpendiculaire à ladite première direction, de manière à permettre un balayage et une stimulation bidimensionnels de ladite couche de substance luminescente stimulable, par ledit rayon de stimulation; et
(f) des moyens pour ramener ledit matériau de support (701) et ladite section de lecture dans ladite position de départ une fois que l'image de rayonnement est lue à partir de ladite couche de substance luminescente stimulable, à la suite de quoi lesdits moyens d'effacement (710) peuvent agir de manière à éliminer l'image de rayonnement subsistant sur ladite couche de substance luminescente stimulable avant un autre enregistrement d'une image sur cette couche.